Telementor2 eyepiece prism

[Ray8]

I have had a Telementor2 telescope with 0.965" eyepieces for about 40 years but now wish to add a right angle converter to make it more comfortable to use. I would welcome advice on what adapter I need and possible sources. What is best, a prism or mirror converter?

[markse68]

You can get all the parts you need from Baader- M44 to T2 adapter ring, (once you have that bit you have loads of choice) T2- 1.25”  eyepiece holder, and/or diagonal although you have lots of choice for 1.25” diagonals. No idea which type is best but the long focal length i think means prisms work fine.

https://www.baader-planetarium.com/en/baader-zeiss-camera-adapter-m44t-2.html

https://www.baader-planetarium.com/en/catalogsearch/result/?q=t2+eyepiece

with that you can use any 1.25” diagonal

or

https://www.baader-planetarium.com/en/baader-zenith-prism-diagonal-t-290-°-with-32mm-prism--(t-2-part-14).html

which will screw straight onto the T2 though if you do that you might want one of their zeiss pattern circular dovetails inbetween to be able to rotate the prism.

https://www.baader-planetarium.com/en/accessories/adapters-imaging-accessories/astro-t2-system/baader-t-2-quick-changer-with-zeiss-micro-bayonet-(t-2-part-06).html

You should be able to get these from most of the UK suppliers. Pricey but good quality. Alternatively you could just look for a 0.956” diagonal that would fit straight into the eyepiece holder of the telementor- not sure if it has enough focus travel for that though.

Mark

[Ray8]

Thanks Mark for your helpful response. I may need something from Baader but rather pricey for my limited use so I may settle for a 0.956" diagonal that fits straight into the eyepiece holder. Perhaps other members will know if there could be problems with the focus travel.

Ray

[Don Pensack]

Even with a 0.965" star diagonal (good luck finding one of those!!), you will need at least an inch of additional in travel at the focuser.

Do you have that?

[markse68]

@Stu probably knows if he’s around

Mark

[Stu]

19 minutes ago, markse68 said:

@Stu probably knows if he’s around

Mark

I have an M44 to T2 adaptor on my Telementor 2, but I’ve also added a 2” Clicklock adaptor to make it easier to use different accessories. There is still enough inwards travel to use a T2 diagonal, and I’ve even used binoviewers with a barlow element.

There might be some useful info here.

A T2 prism would screw directly to the M44 to T2 adaptor obviously which would save plenty of in focus.

[vineyard]

Hello, so I ran two experiments w my 0.96" mirror diagonal.

First I put it in instead of an EP on the straight-through configuration (ie, with the extender tube still attached to the OTAm and the diagonal inserted as if it was an 0.96" EP).  As @Don Pensack says, no joy finding focus.

Second I removed the extender tube and attached the funnel shaped thing which the 0.96" EP would normally slide into directly to the OTA (since it also has the M44 thread).  And then put in the diagonal.  And that did find focus on buildings about 2-3 miles away (too cloudy here for true infinity) with still some travel to go after that.

But I wouldn't be very comfortable w the second configuration b/c its literally only friction thats holding the diagonal in (since the funnel thing doesn't have a set screw or compression band) - I'd be v-e-r-y nervous relying on that alone to hold the diagonal and EPs, and there is no way I would put a BV on that.

So I'd echo @Stu & @markse68 wrt getting something that adapts from M44 down to your diagonal nose, b/c that will be much more secure.

Cheers,

Vin

(PS @sungazer is selling a neat adapter combination for Telementors in the For Sale section in case that's helpful - you'd still need an M44 to T2 adapter)

Edited January 5, 2021 by vineyard
added PS

[Ray8]

I wish to thank everyone who kindly took the time to answer my enquiry. Your suggestions and links are very helpful.

Kind regards

Ray